Trisazo dyes for ink jet printing

ABSTRACT

A composition comprising a liquid medium and a compound of Formula (1) or salt thereof:  
                 
wherein: A is 2-sulpho-4-methoxyphenyl; B is optionally substituted phenylene or naphthylene; n is 0 or 1; and D is a pyrazolonyl group; wherein the liquid medium comprises an organic solvent, inks comprising this composition and printing processes.

This invention relates to compounds suitable for use as dyes, to inksand to their use in ink jet printing (“IJP”). IJP is a non-impactprinting technique in which droplets of ink are ejected through a finenozzle onto a substrate without bringing the nozzle into contact withthe substrate.

There are many demanding performance requirements for dyes and inks usedin IJP. For example they desirably provide sharp, non-feathered imageshaving good water-fastness, ozone-fastness, light-fastness and opticaldensity. The inks are often required to dry quickly when applied to asubstrate to prevent smudging, but they should not form a crust over thetip of an ink jet nozzle because this will stop the printer fromworking. The inks should also be stable to storage over time withoutdecomposing or forming a precipitate which could block the fine nozzle.

JP10195320 describes dyes including tris-azo dyes carrying a pyrazolylazo group and their use in the coloration of paper and pulp.

U.S. patent application 2001/0027734 describes metal complexes oftris-azo dyes derived from tris-azo molecules optionally containing a(substituted) pyrazolylazo moiety.

The copper complexes are said to be particularly preferred.

We have surprisingly found that certain un-metallised compounds providevaluable colorants for ink jet printing inks.

According to the invention, there is provided a composition comprising aliquid medium and a compound of Formula (1) or salt thereof:

wherein:

-   -   A is 2-sulpho-4-methoxyphenyl;    -   B is optionally substituted phenylene or naphthylene;    -   n is 0 or 1; and    -   D is a pyrazolonyl group;        wherein the liquid medium comprises an organic solvent.

The optional substituents on B are preferably selected from carboxy,sulpho, phosphate, optionally substituted amino, acylamino, optionallysubstituted ureido, optionally substituted alkyl, optionally substitutedalkoxy and optionally substituted aryl.

When B is substituted phenylene it preferably carries one or more groupsselected from optionally substituted C₁₋₆-alkyl, optionally substitutedC₁₋₆-alkylthio, optionally substituted C₁₋₆-alkoxy, optionallysubstituted amino, optionally substituted ureido, carboxy and sulphato.When B is optionally substituted naphthylene the naphthylene ringpreferably carries one or more water solubilising groups, morepreferably by one or two groups selected from carboxyl, sulphonic andphosphonic acid groups.

As examples of optionally substituted phenylene and naphthylene groupsrepresented by B there may be mentioned 7-sulphonaphth-1,4-ylene,naphth-1,4-ylene, 2,5-dimethoxyphen-1,4-ylene,2,5-di(2-hydroxyethoxy)phen-1,4-ylene and2-methoxy-5-methylphen-1,4-ylene.

Preferably D is a pyrazolonyl group carrying at least one carboxy,sulpho or phosphato group. In another embodiment, D is preferably apyrazolonyl group of Formula (2a) or Formula (2b):

wherein

-   -   R¹ is H, carboxy, or optionally substituted alkyl, alkoxy, acyl,        aryl, amino or amido; and    -   R² and R³ are each independently H or optionally substituted        aryl or alkyl; and the asterisk * shows the point of attachment        to the azo linkage in Formula (1).    -   R¹ is preferably an optionally substituted C₁₋₆alkyl, C₁₋₆-acyl        or amino group or a group capable of hydrogen bonding with the        adjacent azo group such as carboxy. More preferably R¹ is        carboxy.

Preferred optionally substituted C₁₋₆-alkyl groups are optionallysubstituted C₁₋₄-alkyl, more preferably C₁₋₄-alkyl which isunsubstituted or carries a carboxy, sulpho or phosphato group.

Preferred optionally substituted C₁₋₆-alkoxy groups are optionallysubstituted C₁₋₄-alkyl, more preferably C₁₋₄-alkyl which isunsubstituted or carries a carboxy, sulpho or phosphato group.

Preferred optionally substituted phenyl groups are those mentioned abovefor A. Preferred optionally substituted sulphonamide groups are of theformula SO₂NR⁴R⁵ wherein R⁴ and R⁵ are each independently H, optionallysubstituted C₁₋₆ alkyl.

Preferred optionally substituted amino groups are optionally substitutedacylamino, especially C₁₋₄-acylamino, more preferably optionallysubstituted ureido which is unsubstituted or carries a carboxy, sulphoor phosphato group.

Preferably acyl groups are optionally substituted C₁₋₄alkylacyl,optionally substituted phenylacyl, preferably acetyl or benzoyl.

As examples of groups represented by R¹ there may be mentioned methyl,carboxy and H.

R² and R³ are preferably each independently an optionally substitutedaryl group, more preferably phenyl or phenyl carrying one or twosubstituents selected from carboxy and sulpho.

As examples of groups represented by R² and R³ there may be mentionedphenyl, 3-sulphophenyl and 4-sulphophenyl.

In view of the above preferences, in a preferred embodiment:

-   -   B is phenylene or naphthylene carrying one or two substituents        selected from sulpho, methyl, methoxy and 2-hydroxyethoxy;    -   n is 0 or 1;    -   D is of Formula (2a) or (2b);    -   R¹ is H, methyl or carboxy; and    -   R² and R³ are each independently phenyl or phenyl carrying one        or two substituents selected from sulpho and carboxy.

The compounds of Formula (1) may be prepared by diazotising a compoundof the Formula (3) wherein n, A and B are as hereinbefore defined togive a diazonium salt and coupling the resultant diazonium salt with acompound of Formula H-D wherein D is of Formula (2a) or (2b) ashereinbefore defined:

The diazotisation is preferably performed at a temperature of 0° C. to10° C. Preferably the diazotisation is performed in water, preferably ata pH below 7. Dilute mineral acid, e.g. HCl or H₂SO₄, may be used toachieve the desired pH conditions.

The compound of Formula (3) may be prepared by diazotising a compound ofFormula A-N═N—B—NH₂ to give a diazonium salt and coupling the resultantdiazonium salt with 1-hydroxy-3-sulpho-7-amino naphthylene optionallycarrying a sulpho group at the 5-, 6- or 8-position, wherein A and B areas hereinbefore defined. Reaction conditions are those generally used inthe dyestuff art, for example as described in for example EP 0356080.

When the compound of Formula (1) is in the form of a salt the preferredsalts are alkali metal salts (especially lithium, sodium and potassiumsalts), ammonium and substituted ammonium salts and mixtures thereof.Especially preferred salts are sodium, potassium and lithium salts,salts with ammonia and volatile amines and mixtures thereof.

The lithium salts have good solubility, forming particularly storagestable inks with low toxicity and no tendency to block ink jet nozzles.

The compounds may be converted into a desired salt using knowntechniques. For example, an alkali metal salt of a compound may beconverted into the ammonium or substituted ammonia salt by dissolving analkali metal salt of the compound in water, acidifying with a mineralacid and adjusting the pH of the solution to pH 9 to 9.5 with ammonia orthe amine and removing the alkali metal cations by dialysis or by use ofan ion exchange resin.

Examples of amines which may be used to form such salts includemethylamine, dimethylamine, trimethylamine, ethylamine, n-propylamine,iso-propylamine, n-butylamine, iso-butylamine, sec-butylamine,tert-butylamine, piperidine, pyridine, morpholine, allylamine,diethylamine, triethylamine, tetramethyl amine and mixtures thereof. Itis not essential that the dyes are completely in the form of theammonium salt or substituted ammonium salt and mixed alkali metal andeither ammonium salt or substituted ammonium salt are effective,especially those in which at least 50% of the cations are ammonium orsubstituted ammonium ions.

Still further salts are those with the counter ions described in U.S.Pat. No. 5,830,265, claim 1, integer (b), which are included herein byreference thereto.

The compounds of Formula (1) may exist in tautomeric forms other thanthose shown in this specification. These tautomers are included withinthe scope of the present claims.

A preferred composition comprises:

-   -   (a) from 0.01 to 30 parts of a compound of Formula (1) or salt        thereof; and    -   (b) from 70 to 99.99 parts of a liquid medium;        wherein the liquid medium comprises an organic solvent and all        parts are by weight and the number of parts of (a)+(b)=100.

The number of parts of component (a) is preferably from 0.1 to 20, morepreferably from 0.5 to 15, and especially from 1 to 5 parts. The numberof parts of component (b) is preferably from 99.9 to 80, more preferablyfrom 99.5 to 85, especially from 99 to 95 parts. Preferably component(a) is completely dissolved in component (b). Preferably component (a)has a solubility in component (b) at 20° C. of at least 10%. This allowsthe preparation of liquid dye concentrates which may be used to prepareinks and reduces the chance of the dye precipitating if evaporation ofthe liquid medium occurs during storage.

Preferred liquid media comprise water and an organic solvent, preferablyin a weight ratio of water to organic solvent of 99:1 to 1:99, morepreferably 99:1 to 50:50 and especially 95:5 to 80:20.

It is preferred that the organic solvent is a water-miscible organicsolvent or a mixture of such solvents. Preferred water-miscible organicsolvents include C₁₋₆-alkanols, preferably methanol, ethanol,n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol,n-pentanol, cyclopentanol and cyclohexanol; linear amides, preferablydimethylformamide or dimethylacetamide; ketones and ketone-alcohols,preferably acetone, methyl ether ketone, cyclohexanone and diacetonealcohol; water-miscible ethers, preferably tetrahydrofuran and dioxane;diols, preferably diols having from 2 to 12 carbon atoms, for examplepentane-1,5-diol, ethylene glycol, propylene glycol, butylene glycol,pentylene glycol, hexylene glycol and thiodiglycol and oligo- andpoly-alkyleneglycols, preferably diethylene glycol, triethylene glycol,polyethylene glycol and polypropylene glycol; triols, preferablyglycerol and 1,2,6-hexanetriol; mono-C₁₋₄-alkyl ethers of diols,preferably mono-C₁₋₄-alkyl ethers of diols having 2 to 12 carbon atoms,especially 2-methoxyethanol, 2-(2-methoxyethoxy)ethanol,2-(2-ethoxyethoxy)-ethanol, 2-[2-(2-methoxyethoxy)ethoxy]ethanol,2-[2-(2-ethoxyethoxy)-ethoxy]-ethanol and ethyleneglycol monoallylether;cyclic amides, preferably 2-pyrrolidone, N-methyl-2-pyrrolidone,N-ethyl-2-pyrrolidone, caprolactam and 1,3-dimethylimidazolidone; cyclicesters, preferably caprolactone; sulphoxides, preferably dimethylsulphoxide and sulpholane. Preferably the liquid medium comprises waterand 2 or more, especially from 2 to 8, water-soluble organic solvents.

Especially preferred water-soluble organic solvents are cyclic amides,especially 2-pyrrolidone, N-methyl-pyrrolidone and N-ethyl-pyrrolidone;diols, especially 1,5-pentane diol, ethyleneglycol, thiodiglycol,diethyleneglycol and triethyleneglycol; and mono-C₁₋₄-alkyl andC₁₋₄-alkyl ethers of diols, more preferably mono-C₁₋₄-alkyl ethers ofdiols having 2 to 12 carbon atoms, especially((2-methoxy-2)-ethoxy)-2-ethoxyethanol.

The dyes of the invention may be used as the sole colorant in inksbecause of their attractive black shade. However, if desired, one maycombine the present compounds with one or more further colorants if aslightly different shade is required for a particular end use. Thefurther colorants are preferably dyes. When further colorants areincluded in the ink these are preferably selected from black, magentaand yellow colorants and combinations thereof.

Suitable further black colorants include C.I.Food Black 2, C.I.DirectBlack 19, C.I.Reactive Black 31, PRO-JET™ Fast Black 2, C.I.Direct Black195; C.I.Direct Black 168; and black dyes described in patents byLexmark (e.g. EP 0 539,178 A2, Example 1, 2, 3, 4 and 5), OrientChemicals (e.g. EP 0 347 803 A2, pages 5-6, azo dyes 3, 4, 5, 6, 7, 8,12, 13, 14, 15 and 16) and Seiko Epson Corporation.

Suitable further magenta colorants include PRO-JET™ Fast Magenta 2.

Suitable further yellow colorants include C.I.Direct Yellow 142;C.I.Direct Yellow 132; C.I.Direct Yellow 86; C.I.Direct Yellow 85;C.I.Direct Yellow 173; and C.I.Acid Yellow 23.

The ink may also contain additional components conventionally used inink jet printing inks, for example viscosity and surface tensionmodifiers, corrosion inhibitors, biocides, kogation reducing additivesand surfactants which may be ionic or non-ionic.

The pH of the composition is preferably from 4 to 11, more preferablyfrom 7 to 10. The viscosity of the composition at 25° C. is preferablyless than 50 cP, more preferably less than 20 cP and especially lessthan 5 cP.

When the compositions according to the invention are used as ink jetprinting compositions, the composition preferably has a concentration ofhalide ions of less than 500 parts per million, more preferably lessthan 100 parts per million. It is especially preferred that thecomposition has less than 100, more preferably less than 50 parts permillion of divalent and trivalent metals, wherein parts refer to partsby weight relative to the total weight of the composition. We have foundthat purifying the compositions to reduce the concentration of theseundesirable ions reduces nozzle blockage in ink jet printing heads,particularly in thermal ink jet printers.

According to the second aspect of the present invention there isprovided a compound of Formula (1) with the proviso that when A isoptionally substituted phenyl, A is free from nitro groups. Thepreferences for A, B, n and D in dyes according the second aspect of thepresent invention are as described above in relation to thecompositions, with the proviso that A is free from nitro groups when Ais optionally substituted phenyl.

A further aspect of the invention provides a process for printing animage on a substrate comprising applying thereto a composition accordingto the first aspect of the present invention to the substrate by meansof an ink jet printer.

The ink jet printer preferably applies the composition to the substratein the form of droplets which are ejected through a small orifice ontothe substrate. Preferred ink jet printers are piezoelectric ink jetprinters and thermal ink jet printers. In thermal ink jet printers,programmed pulses of heat are applied to the composition in a reservoirby means of a resistor adjacent to the orifice, thereby causing thecomposition to be ejected in the form of small droplets directed towardsthe substrate during relative movement between the substrate and theorifice. In piezoelectric ink jet printers the oscillation of a smallcrystal causes ejection of the composition from the orifice.

The substrate is preferably paper, plastic, a textile, metal or glass,more preferably a treated substrate such as a coated paper or coatedplastic, especially coated paper. Preferred plain or treated papers arepapers which may have an acid, alkaline or neutral character. Examplesof commercially available treated papers include HP Premium CoatedPaper, HP Photopaper (both available from Hewlett Packard Inc.); StylusPro 720 dpi Coated Paper, Epson Photo Quality Glossy Film, Epson PhotoQuality Glossy Paper (all available from Seiko Epson Corp.); Canon HR101 High Resolution Paper, Canon GP 201 Glossy Paper, Canon HG 101 andHG201 High Gloss Film and Canon PR101 (all available from Canon).

A further aspect of the present invention provides a paper, an overheadprojector slide or a textile material printed with a composition, acompound or by means of a process as hereinbefore defined.

A still further aspect of the present invention provides an ink jetprinter cartridge, optionally refillable, comprising one or morechambers and a composition, wherein the composition is present in atleast one of the chambers and the composition is according to the secondaspect of the present invention.

The present compounds and compositions provide prints of attractive,neutral black shades which are particularly well suited for the ink jetprinting of text and images. The compositions have good storagestability and low tendency to block the very fine nozzles used in inkjet printers. Furthermore, the resultant images have good opticaldensity, light-fastness, wet-fastness and resistance to fading in thepresence of oxidising air pollutants. This is achieved without the needfor copper or other transition metals used in the dyes of U.S.2001/0027734. As a result the dyes of the present invention are simplerto make and more environmentally friendly than the metallised dyes ofU.S. 2001/0027734.

The invention is further illustrated by the following Examples in whichall parts and percentages are by weight unless specified otherwise.

EXAMPLE 1

Preparation of

Stage A

2-Sulpho-4-methoxyaniline (20.3 g, 0.1M) was stirred in water (150 ml)at room temperature and 2N NaOH added to form a solution at pH 8.0. 2NNaNO₂ solution (50 ml) was added and the mixture stirred to homogenise.The solution was added gradually to a mixture of ice/water (150 ml) and36% HCl (40 ml) at 5° C. and the resulting suspension stirred for 2hours at 0-10° C. Sulphamic acid solution (10%) was added in order toremove excess nitrous acid.

2,5-Dimethoxyaniline (28.5 g, 0.1M) was dissolved in water (300 ml) andcooled to room temperature. The resulting suspension was added to theabove diazo suspension at 0-10° C. and the pH adjusted to 4.5 by theaddition of sodium acetate. The mixture was stirred for 18 hours and thedye collected by filtration and washed with water (100 ml).

Stage B

The paste from Stage 1 (0.1M) was dissolved in water (100 ml) and 2NNaOH solution at pH 9.0. 2N NaNO₂ solution (50 ml) was added and themixture stirred for 3 minutes. The solution was added gradually to amixture of ice/water (150 ml) and 36% HCl (40 ml) at 5° C. using rapidagitation. The resulting suspension was stirred 1h at 5° C. Sulphamicacid solution (10%) was added in order to remove excess nitrous acid.

Gamma acid (23.9 g, 0.1M) was dissolved in water (150 ml) and 2N NaOHsolution at pH 9.0. Na₂CO₃ (10 g) was added and the solution cooled to0-10° C. To this was added the above diazo suspension, while holding thepH at 9.5 to 10 with 20% Na₂CO₃ solution. The solution was stirred for 1hour at 0-10° C. and the pH adjusted to 5.5 by the addition of glacialacetic acid.

The precipitated dye was collected by filtration and washed with diluteacetic acid solution (5%). The paste was redissolved in water (150 ml)and 2N NaOH solution at pH 9.0. The solution was heated to 50° C. andNaCl (15% w/v) added and the precipitated dye collected by filtrationand washed with 20% NaCl solution (100 ml).

Stage C

The product obtained by following Stage B (12.7 g) and sodium nitrite(1.52 g) were dissolved in water (400 ml). The solution was added to amixture of ice-water (50 g) to which hydrochloric acid (7 ml) had beenadded. The mixture was then stirred for 2 hrs maintaining thetemperature below 10° C. to effect diazotisation. At the end of thistime the excess nitrous acid was destroyed by the addition of sulphamicacid. The resultant diazonium salt suspension was then slowly added to asolution of 1-(4-sulphophenyl)-5-pyrazolone-3-carboxylic acid (4.51 g,obtained from Pfaltz & Bauer) in water (200 ml) at pH 7 (lithiumhydroxide) at 0-10° C., maintaining the pH at 6-7 by addition of lithiumhydroxide (2 M). After stirring for a further 1 hour the temperature wasraised to 30° C. and lithium chloride 25% w/v was added (exothermic).The stirred suspension was allowed to self-cool to 50° C. and theproduct was then isolated by filtration. After washing with lithiumchloride solution (1l, 30% w/v) the product was further purified bydissolving in water (500 ml) and adding acetone (1l). The title producthas then isolated by filtration, washed with acetone, dissolved inwater, dialysed to low conductivity before evaporating to dryness.

EXAMPLE 2

The method of Example 1 was repeated except that 2,5-dimethoxyaniline inStage A was replaced by 2-methyl-5-methoxyaniline.

EXAMPLE 3

The method of Example 1 was repeated except that 2,5-dimethoxyaniline inStage A was replaced by 2,5-diacetoxyethoxyaniline.

EXAMPLE 4

The method of Example 3 was repeated except that Gamma acid in Stage Bwas replaced by 1-hydroxy-8-amino-3,6-naphthylene disulphonic acid.

EXAMPLE 5 Inks

Inks were prepared containing the dyes from Examples 1 and 3 accordingto the following formulation: 2-Pyrrolidone   5 parts Thiodiglycol   5parts Surfynol ™ 465   1 part Dye 3.5 parts Water amount required tomake up to 100 parts

Surfynol™ 465 is a surfactant available from Air Products and ChemicalsInc., USA. Further inks were prepared according to Tables 1 and 2wherein the dye described in the first column is the dye made in theabove example of the same number. Numbers quoted in the second columnonwards refer to the number of parts of the relevant ingredient and allparts are by weight. The inks may be applied to paper by thermal orpiezo ink jet printing.

The following abbreviations are used in Tables 1 and 2:

-   -   PG=propylene glycol    -   DEG=diethylene glycol    -   NMP=N-methylpyrollidone    -   DMK=dimethylketone    -   IPA=isopropanol    -   MEOH=methanol    -   2P=2-pyrollidone    -   MIBK=methylisobutyl ketone    -   P12=propane-1,2-diol    -   BDL=butane-2,3-diol    -   CET=cetyl ammonium bromide    -   PHO=Na₂HPO₄    -   TBT=tertiary butanol

TDG=thiodiglycol TABLE 1 Dye Na Dye Content Water PG DEG NMP DMK NaOHStearate IPA MEOH 2P MIBK 1 2.0 80 5 6 4 5 2 3.0 90 5 5 0.2 3 10.0 85 33 3 5 1 4 2.1 91 8 1 1 3.1 86 5 0.2 4 5 2 1.1 81 9 0.5 0.5 9 3 2.5 60 415 3 3 6 10 5 4 4 5 65 20 10 1 2.4 75 5 4 5 6 5 2 4.1 80 3 5 2 10 0.3 33.2 65 5 4 6 5 4 6 5 4 5.1 96 4 1 10.8 90 5 5 2 10.0 80 2 6 2 5 1 4 31.8 80 5 15 4 2.6 84 11 5 1 3.3 80 2 10 2 6 2 12.0 90 7 0.3 3 3 5.4 69 220 2 1 3 3 4 6.0 91 4 5

TABLE 2 Dye Dye Content Water PG DEG NMP CET TBT TDG BDL PHO 2P PI2 13.0 80 15 0.2 5 2 9.0 90 5 1.2 5 3 2.0 90 10 4 2 88 10 1 5 78 5 12 5 2 870 2 8 15 5 3 10 80 10 8 12 4 10 80

EXAMPLE 6 Ink Jet Printing

The inks described in Example 5 were ink-jet printed onto a variety ofpapers using a Hewlett Packard DeskJet 560C™. The CIE colourco-ordinates of each print (a, b, L, Chroma (C) and hue (H)) weremeasured using a Gretag Spectrolino Spectrodensitometer™ with 0°/45°measuring geometry with a spectral range of 400-700 nm at 20 nm spectralintervals, using illuminant D50 with a 2° (CIE 1931) observer angle anda density operation of status A. No less than 2 measurements were takendiagonally across a solid colour block on the print with a size greaterthan 10 mm×10 mm. The properties of the resultant prints are shown inTable 3, where the example number of the dye used to prepare the ink isindicated in the left hand column.

The substrates used in Tables 3, 4 and 5 were as follows: SubstrateSubstrate Number: Xerox 4024 ™ 1 HG 201 ™ 2 PR101 ™ MkII 3 HP PremiumPlus ™ MkII 4 SEC Premium Photo ™ 5

TABLE 3 Dye Example No. SUBSTRATE ROD L a b C H 1 1 1.08 35 −5 −3 5 2081 2 2.14 7 −5 −4 6 219 1 3 1.91 11 −4 −8 9 241 1 4 2.12 7 −5 −2 5 201 15 1.86 12 −6 −5 8 220 3 1 1.05 36 −5 −2 5 206 3 2 2.08 8 −6 −3 6 203 3 31.69 16 −6 −6 8 227 3 4 1.96 10 −6 −1 6 193 3 5 1.71 16 −7 −2 7 198Light-Fastness:

To evaluate light fastness the prints described in Table 3 wereirradiated in an Atlas Ci5000 Weatherometer™ for 100 hours. The resultsare shown in Table 4 where the example number of the dye used to preparethe ink is indicated in the left hand column. The degree of fade isexpressed as ΔE where a lower figure indicates higher light fastness,and ΔE is defined as the overall change in the CIE colour co-ordinatesL, a, b of the print and is expressed by the equationΔE=(ΔL²+Δa²+Δb²)^(0.5). TABLE 4 Dye Example No. SUBSTRATE ΔE 1 1 19 1 265 1 3 28 1 4 12 1 5 5 3 1 17 3 2 61 3 3 27 3 4 14 3 5 4Ozone-Fastness:

The inks prepared in Example 4 were printed onto the substratesindicated in Table 5 using a HP560™ ink jet printer. The printedsubstrates were then assessed for ozone fastness using an ozone testcabinet from Hampden Test Equipment. The exposures to ozone were carriedout for 24 hours at 40° C. and 50% relative humidity in the presence of1 part per million of ozone. Ozone-fastness was judged by measuring theoptical density before and after exposure to ozone using a GretagSpectrolino Spectrodensitometer™. Thus, the lower the % OD loss thegreater the ozone fastness. The results are shown in Table 5 where theexample number of the dye used to prepare the ink is indicated in theleft hand column. These clearly demonstrate that inks based oncompositions of this invention display good ozone fastness. TABLE 5 Dye% Example OD No. SUBSTRATE LOSS 1 1 3 1 2 28 1 3 33 1 4 0 1 5 11 3 1 2 32 23 3 3 28 3 4 4 3 5 10

1. A composition comprising a liquid medium and a compound of Formula(1) or salt thereof:

wherein: A is 2-sulpho-4-methoxyphenyl; B is optionally substitutedphenylene or naphthylene; n is 0 or 1; and D is a pyrazolonyl group;wherein the liquid medium comprises an organic solvent.
 2. A compositionaccording to claim 1 wherein D is a pyrazolonyl group carrying at leastone carboxy, sulpho or phosphato group.
 3. A composition according toeither claim 1 or claim 2 which contains a further colorant selectedfrom black, magenta and yellow colorants and combinations thereof.
 4. Acomposition according to claim 1 wherein: B is phenylene or naphthylenecarrying one or two substituentsselected from sulpho, methyl, methoxyand 2-hydroxyethoxy; n is 0 or 1; D is of Formula (2a) or (2b); R¹ is H,methyl or carboxy; and R² and R³ are each independently phenyl or phenylcarrying one or two substituents selected from sulpho and carboxy.
 5. Acompound of Formula (1) as defined in claim
 1. 6. A compound accordingto claim 5 wherein B is phenylene or naphthylene carrying one or twosubstituents selected from sulpho, methyl, methoxy and 2-hydroxyethoxy;n is 0 or 1; D is of Formula (2a) or (2b); R¹ is H, methyl or carboxy;and R² and R³ are each independently phenyl or phenyl carrying one ortwo substituents selected from sulpho and carboxy.
 7. A process forprinting an image on a substrate comprising applying thereto acomposition according to claim 1 by means of an ink jet printer.
 8. Apaper, an overhead projector slide or a textile material printed with acompound of Formula (1), or composition containing same, according toclaim
 1. 9. An ink jet printer cartridge, optionally refillable,comprising one or more chambers and a composition, wherein thecomposition is present in at least one of the chambers and thecomposition is as defined in claim
 1. 10. A paper, an overhead projectorslide or a textile material printed by a process according to claim 7.